Hemangiosarcoma in Dogs


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Many first-time dog owners don’t realize that dogs are just as susceptible to disease and illness as people can be. In fact, many are shocked to discover that dogs can get the flu, get colds, have allergies, and be diagnosed with cancer. One of the most common types of cancer that dogs experience is cancer of the spleen, followed by cancer of the liver. Liver and spleen cancers are collectively referred to as hemangiosarcoma. This guide will help you understand everything you need to know about these cancers, including:

  • What causes hemangiosarcoma in dogs
  • Hemangiosarcoma dog symptoms
  • Diagnosis of hemangiosarcoma in dogs
  • Canine hemangiosarcoma treatment
  • Prevention of hemangiosarcoma in dogs

Considering that around half of all cancer diagnoses in dogs are in the spleen, and around 5% of all cancer diagnoses in dogs are in the liver, hemangiosarcoma is far more common than you might think. Here’s what you need to know about these cancers to keep your dog safe and healthy.

What is Hemangiosarcoma? The 3 Types of Hemangiosarcoma

Hemangiosarcoma is technically cancer that starts in the tissue that surrounds the heart, blood vessels, and lymph nodes of your dog. Once cancer invades the blood vessels, it has a direct highway to any part of the body. But because blood is cycled through the spleen and liver to be cleaned, these are the areas where the cancer is usually detected.

There are three types of hemangiosarcoma:

  • Dermal: This type shows up on the surface of the skin, where the cancerous tumor can be removed quite easily. These will appear as growths on the skin, not like a lump under the skin. They may show up anywhere on your dog’s body.
  • Subcutaneous: This type shows up just under the surface of the skin, where the tumor can be seen as a dark spot with growth just under the skin. These frequently spread to the internal bodily systems. These can often be seen anywhere on the body.
  • Visceral: This is the least common type of hemangiosarcoma, in which malignant tumors develop on the liver, spleen, heart, lungs, kidneys, bones, bladder, uterus, muscles, or basically any other organ.

What Causes Hemangiosarcoma in Dogs?

For the most part, we don’t know what causes a dog to develop subcutaneous or visceral hemangiosarcoma. Being exposed to certain toxins, and genetics, play a role in the development of cancer in dogs. However, we do know that prolonged sun exposure can be the cause of dermal hemangiosarcoma. Just like skin cancer in humans, over-exposure to UV rays can cause skin growths that are cancerous. We do know that male dogs seem to be more likely to have hemangiosarcoma, though the cause isn’t understood.

The reason we know so little about what causes hemangiosarcoma is that it’s not cancer that affects humans. Our research on this cancer is very limited, and the only concrete data we have is that exposure to vinyl chloride – or the PVC that makes pipes and coats wires and cables – could be linked to this type of cancer.

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Hemangiosarcoma Dog Symptoms

The symptoms of hemangiosarcoma can vary drastically depending on the type and the dog. Unfortunately, the most severe kind of hemangiosarcoma often doesn’t have visible symptoms until the cancer has developed beyond the point of treatment. Some signs of hemangiosarcoma include:

  • Internal bleeding, which may show up as bloody feces or urine
  • Lumps under the skin or on the surface of the skin
  • Weakness
  • Pale gums
  • Seizures
  • Depression
  • Inability to walk at times
  • Swelling of the abdomen
  • Trouble with breathing
  • Nosebleeds
  • Being often tired
  • Bleeding that doesn’t seem to stop
  • Dark-colored spots on the skin accompanied by lumps
  • Abnormal heartbeat
  • Pain in the joints
  • Swollen ribs
  • Weight loss
  • Seeming confused or regressing to untrained, puppy behavior
  • Blood loss

Most of these symptoms are related to growths pressing against vital organs or internal bleeding that is already taking place, which means that by the time you see the symptoms, it is not a good sign at all. That is why it is very important to take even a small sign that something may be wrong very seriously. The outlook for a hemangiosarcoma diagnosis is not the greatest, so early treatment is very important.

Dog Breeds Prone to Hemangiosarcoma

There are certain dogs that are much more prone to developing hemangiosarcoma than others. For example, larger dogs like German Shepherds, Boxers, Dobermans, Labrador and Golden Retrievers, and English Setters, are all more prone to these cancers. Dogs that are a little bit older, past six years of age, are also more likely to be diagnosed with hemangiosarcoma. By far the most common type of hemangiosarcoma is cancer of the spleen, although the tumors can spread to many other organs.

Diagnosis of Hemangiosarcoma in Dogs

To diagnose hemangiosarcoma, a vet goes through a thorough examination. They will start by looking at the gums. Pale gums are a very good indication that there is a bleeding problem going on internally. They will check for swelling and lumps all around the dog’s body, paying close attention to the area where the heart and lungs are. They will draw some blood and watch your dog to see if the area clots quickly.

The blood that is drawn will be sent off to a lab to have a blood count performed, and the vet may also do a urinalysis to eliminate the possibility of viral or bacterial infections. Chest x-rays may be taken to determine how much fluid is built up around the dog’s organs. These x-rays may also be able to help the vet identify tumors inside the body, which can not only help with diagnosis but can also help the vet determine the best course of treatment in the future.

These things can help a vet to make an educated diagnosis about your pet’s hemangiosarcoma. However, the only way to know for sure without a doubt is to do a biopsy of visible tumors. The problem with this is that the tumor could hemorrhage during the procedure, and if your pet is having issues with blood clotting, this could be life-threatening. More than likely, your vet will diagnose the hemangiosarcoma using the x-rays and blood work, and will then walk you through the treatment options. If surgery is part of what you choose to pursue, a biopsy of the removed tumor will likely be part of the process.

Canine Hemangiosarcoma Treatment

There is a different treatment option for each type of hemangiosarcoma. The most successful treatment is for dermal hemangiosarcoma, which often just involves removing the tumor and watching the removal site to ensure that it heals properly. This is often very successful and easy. If the vet can’t get rid of the entire tumor, or they are worried that the cancer may spread, they can use chemotherapy or radiation therapy to help kill off the rest of the cancer cells. Chemo is often the go-to treatment for subcutaneous hemangiosarcoma as well because it offers the best odds for long-term survival.

However, if your dog has the visceral type of hemangiosarcoma, in which the cancer is in the internal systems, the treatment options are more complicated. If the tumor is very easy to spot and in a good location, the vet may recommend surgical removal. This is especially important if the tumor is near the heart or is putting pressure on the lungs.

Another option is to use a pericardial tap to drain fluid out of the abdomen to keep the heart and lungs healthy. This can help keep your dog more comfortable while chemotherapy is used to treat this type of hemangiosarcoma. Radiation therapy is not effective for visceral hemangiosarcoma. The commonly used chemotherapy medicines for this type include: Cytoxan, doxorubicin, cyclophosphamide, and vincristine. Once again, chemo has the best prognosis for long-term survival when it comes to this type of hemangiosarcoma.

Finally, your vet will attempt to treat the symptoms of the hemangiosarcoma while working on treating the cancer itself. Bleeding disorders, weight loss, problems with weakness or depression, and other symptoms, can be managed with a variety of treatments, such as administered fluids or feeding through a tube.

Unfortunately, the long-term outlook for any of the three types of hemangiosarcoma isn’t really that great. Dogs with dermal hemangiosarcoma may do fine, but it’s common for cancer to return later. Dogs with internal hemangiosarcoma don’t have the best odds of living past two months after diagnosis and surgery. Chemotherapy may add another eight months to that time frame for most dogs. However, with chemo, most owners of dogs with hemangiosarcoma report that their dogs have a better quality of life during the time that they do have.

One of the biggest reasons that dogs don’t often survive hemangiosarcoma is that the blood clotting disorder that results from the cancer is very life-threatening. With this condition, dogs are more prone to internal bleeding, and a decrease in white blood cells that keep them healthy. These dogs are more likely to be sick from other infections due to this side effect of the cancer.

Prevention of Hemangiosarcoma in Dogs

There is no known prevention for visceral hemangiosarcoma in dogs. This condition is likely based more on genetics than anything. However, dermal hemangiosarcoma may be prevented by ensuring that your dog isn’t allowed to get an excessive amount of sun exposure. Doggie sunscreen, breaks in the shade, and keeping them indoors in the hottest parts of the summer, can protect their skin from this cancer.

Otherwise, there is no way to prevent this cancer. Instead, all you can do is watch for the signs of this cancer, and get your dog to the vet right away. Early treatment is the best way to help prolong your dog’s life.

Will Hemangiosarcoma Ever Be Cured?

There are many studies going on in the veterinary world about hemangiosarcoma and whether we can find a cure for it. There are certain medications being developed that help to prevent the blood clotting disorder that causes the eventual shortened lifespan of a dog that was successfully treated for hemangiosarcoma. This could be the breakthrough that helps make survival rates higher, though these medications are still in testing phase.

Other things like molecule inhibitors are also being studied, but there is no definitive cure on the market today.

In Summary

To sum up this guide to hemangiosarcoma, here’s what you need to know:

  • Hemangiosarcoma is a type of cancer that dogs can get that primarily impacts the spleen and liver.
  • Hemangiosarcoma comes in three types: tumors that sit on top of the skin, tumors that grow just under the skin, and tumors that develop internally. The third type is the most dangerous.
  • Large breed dogs and middle-aged dogs are more likely to develop hemangiosarcoma.
  • While there are ways to treat hemangiosarcoma, the long-term survival rates for this cancer are slim. This is due to the fact that one common symptom of the cancer is a blood clotting disorder that puts dogs at risk.
  • Chemotherapy and surgery are the two most effective means of treating hemangiosarcoma, with chemotherapy offering a slightly longer survival rate after the fact.
  • The veterinary community is working to create a cure that keeps dogs recovering from hemangiosarcoma from dying of side effects like blood clotting disorders.

Final Word

Overall, this is not a very hopeful diagnosis. However, if your dog is diagnosed with hemangiosarcoma, you do have options. If you are able to get the chemotherapy started early enough, your dog may avoid the symptoms that so frequently lead to death later. Additionally, if your dog simply has dermal hemangiosarcoma, surgery may prove to be effective long-term.

If you have a dog, and particularly a middle-aged, large breed dog, and you notice any of the symptoms that could be related to this type of cancer, it is vital that you get them to the vet right away. Early treatment is key for getting the most time that you can with your dog.

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